Two-stroke internal-combustion engine



Jan. 2l, 1930. M. TRECHSEL 1,744,249

f l TWO-STROKE INTERNAL COMBUSTION ENGINE Filed May 21, 1923 'WIA MV1-:NTD Fg: bhw JM BY GM @@@RWM -ATVU RN Ys 'Y pipes. l

The gear controlling the exhaust valve or UNITED STATES PATE-Nr oF'FiCE :aux TRncHsnL, or WINTERTHUR, SWITZERLAND, AssIGNoR 'ro 'rnc :FIRM sULzER FRERES socIT ANONYRIE, oF wnr'rnn'rnun, SWITZERLAND :nwo-s'rnoinszy mrEaNAL-coHRUsrIoN ENQINE Animation mea myl 21, 1928, serial im? 279,427, and in switzeriaafuay 28,1927.

This-invention relates to two-stroke interf nal-combustion engines and has for its objecty to provide an engine in which the dischar e of the exhaust gases can be more eliicienty controlled than hitherto. Y l 4 According to this invention the exhaust is divided into two or more ports or. groups vof ports which are successively'opened or closed y the piston, andthe ports in the upper group orgroups are provided with one or more closinY members.' This not onl enables a stepy-'stepl or progressive disc arge of the exhaust vases to take place but further permits a stepfb increase in the uration of the air=charging period while the exhaust .ports are closed. The valve or .valves controlling the upper exhaust ports may be positively operatedl and the ports through which air is admitted to according to the use to which these gases are.

to be put and the the volume of the exhaust gases to vbe carried away.A The gases escape ing through' the uper' and lower exhaust ports may be carrie valves may cooperate with the gear controlling the supply of airl to .the inlet ports in Such a manner thatjachange in the period during which the exhaust ports are open or closed brings about a corres onding change in the opennnpr closin o the valve controlling. the a ission o air.

To prevent the exhaust gases from entering the air supply pipe inthe event ofthe valve controlling t e upper exhaust ports failing to open, the air supply pipe may be (gf-step or gradually variable l vided with aconnecting rod 3, air being supthe cylinder may also be'provided with a. f valve, and, like the exhaust ports, are pref# erably divided intol twof groups, the upper.

'and lower groups 10 and 1l which are sucp 70 away through separate lroller 20 an One construction according to the inventionis illustrated somewhat diagrammatically by 4Way of example in'. the accompanying drawings, in which-f l Figuresl is averticall section of the cylinder ofda two-stroke internal combustion engine, an Figures 2 and 3 show in sectional elevation and plan respectively a special construction of the gear controlling the valve inthe exhaust pipe. l

I' The engine cylinder l1 has a piston 2 proplied bythe pipe 4 to portsv and 6 arranged in suv erimpo'sed groups.. The ports 6 are -provi edwlth a closing member 7 which is controlled by thecams'haft 8, and if desired the 'airadmitted through the upper ports 6 may be supplied through a separate pipe 9.

The exhaust ports are divided into upper cessively covere Aby the engine piston 2, the upper ports 10 being provided with a closing member 12.r The exhaust gases which escape through theupper ports 10 may be discharged througha separate pipe 14 which may have a val've or throttle 25.l The member 12 is controlled by a shaftl, having a cam 16 which actuates a lever17 connected to the valve 12; The cam 16 o crates thelever 17 through a the setting of this canv be changed by movinga bell crank lever 21 con nected to the governor (not Shown) In the air supply pipe 4 a safety device in the form of a check valve 30 is provided to prevent admission of exhaust gases into the air suply pipe, should for instance the upper'ex haust valve 12 failto close in time. If the combustiony gases are to be fullyuti-` lized in-any desired manner, for vinstance in a' waste gas turbine, the valve 12 opens to allow the exhaust gases to pass through' the ports 10 e0 I vwThe gear controllin terized b the provision of a separate exhaust conduit or each set of exhaust ports.

5. Apparatus according to claim l, characterized b the provision of a separate supply conduit or each set of inlet ports.

6. Apparatus according to claim 1, characterized by the provision of a safety valve adapted to close the inlet ports when 'the exhaust port valve member fails to open.

lIn testimony whereof I have atlixed my signature.

MAX TRECHSEL.

f pipe lopens later in the o cle'than the exhaust rts, i. e. during the escent of the piston.

y he point at which the c am 8 engages the roller 18 of the lever controlling this valve can be adjusted by means of a bell crank lever 19 and any known connection may be provided between the gears controlling the valves '20 7 and 12to4 ensurev the'later closing of the valve 7 shouldv the exhaust valve l2l open earlier and vice versa. A y Instead of varying the point at-whioh the rollers 18 and 20 engage their respective cams asin the arrangement shown in Figure 1 and f ,above described, a conical cam 22 longitudinally adjustable on a camshaft 15 may be em ployed as shown in Figure 2.' 'This adjustment of the cam is conveniently effected by a 3 lever 23 pivoted at 26. Figure 3) and controlled'bythe governor not shown) y The division of the ex aust ports as above described into two groups which are successively uncovered by the piston, has this fur- 3.5 ther'special advantage over engines with one set of valve controlled ,exhaust ports, that in the event of thel valve controlling the upper exhaust ports failing to open, the lower ports still provide ameansA of escape for the exhaust gases.

I claim:

1. In an internal combustion engine, the combination of-a cylinder having spaced sets of inlet ports adaptedto be placed in communication and spaced sets of Aexhaust ports adapted to be placed in communication, a piston movable in said cylinder and controlling said ports,I a valve member for controlling the communication between said sets of inlet ports, a valve member for controlling the communication between said sets of exhaust ports, and control means for said valves adapted to provide inlet and exhaust periods in accordance with the load on'the engine.

2. Apparatus accordingl to claim 1, characterized by the provision of control` means for the valves adapted to provide reciprocal displacement of the inlet and exhaust periods.

3. Apparatus according to claim 1, characterized by the provision of control means for the valves adapted to'provide variation of the length of the inlet'and exhaust periods. l

65 4. Apparatus according to claim l charac- 

